Mr. S

So I have a little problem... I like one of my kid's parents... let's call him Mr. S.
Mr. S is off limits. He's not involved with anyone, young, cutish, and shy... however, not only does he have a 5 year old son, but he has this child with a girl I have known since I was 9. A sister of a girl that's my age... she's not in the picture, but this still makes things awkward. I keep thinking he's trying to flirt with me and I know I make him nervous - I can feel it. I have this urge to kiss him...
I wanna make him break out of his calm shell and see what he's like when he's wild. I have a feeling he has this dark side that I wanna experience. I'm screwed. The first guy I end up liking and he's unattainable.